The two tracks, recorded in 1946, long before singer and harmonica player Terry and guitarist McGhee became well-known in the folk and blues worlds, showed up on one of more than 10,000 16-inch lacquer discs that were part of the UMG donation. The collection had been undergoing cataloging and organizing by a pair of interns working for the library’s Packard Campus for Audio-Visual Conservation in Culpeper, Va.

“A lot of these discs may have some grease pencil labeling on them -- they might say ‘B. Crosby,’ for Bing Crosby,” Matthew Barton, curator for the library’s recorded sound division, told The Times on Thursday. “Most of them have two or three tracks on the discs, and there might be an arrow pointing to the track they decided to use.”

He said interns Katie Rodda and Jacob Houser have been charged with correlating the discs with a master discography of the inventory that was compiled 10 or 12 years ago. “We got these from Universal in 75 or 80 boxes. The documentation was very minimal. We had a single spreadsheet to work with, and it was hard to tell things apart. You couldn’t tell where one session began or ended.”

The Sonny Terrry & Brownie McGhee tracks turn out to be audition sessions they recorded on the same disc that contained a track on which they were playing in support of blues singer and guitarist Josh White.

The titles of the two songs are unknown, Barton said -- there was no information on either included on the disc or within the discography, which didn’t even cite the two Terry-McGhee tracks. In fact, the labeling lists it as “McGee Sanders Aud.,” apparently a reference to Sonny Terry’s given name: Saunders Terrell.

Decca executives apparently were less than impressed -- Terry and McGhee, even though they had played sessions accompanying Woody Guthrie before this 1946 audition, left without a record contract. They didn’t develop a significant following as a duo until the '50s, when they got swept up in the folk music revival.

“I can’t prove it but it’s quite likely that [folklorist] Alan Lomax had a hand in these sessions,” Barton said. “He was already working for Decca by that time.”

And how did two twentysomething interns respond to the discovery?

“They thought it was cool,” Barton said. “Katie, who actually found them, she’s a music student, so she really appreciated it. So did Jacob. But it’s kind of interesting -- being 51, I’m sometimes working with people who are 22 or 23 and realizing, 'Hey, they don’t know Bing Crosby, let alone a couple of blues musicians.' "